1. Field of the Invention
The present invention relates to a night vision device. More particularly, the present invention relates to a night vision device of the ANVIS (aviator's night vision imaging system) type, including a pair of monocular night vision scopes which are mounted and associated with one another in such a way as to provide the user of the device with binocular vision, thereby allowing the user to enjoy a night-time view with depth perception. Still more particularly, the present invention relates to such an ANVIS type of night vision device in which the stability of the monocular night vision scopes on their support structure is greatly improved to virtually eliminate wobble of these scopes and to provide the user with an image of much improved stability.
2. Related Technology
A conventional binocular night vision device is known as the ANVIS, model number AN/AVS-6, hereinafter referred to as the ANVIS 6. The ANVIS 6 includes a pair of night vision monoculars suspended in front of the user's eyes by a laterally elongate frame which is rectangular in plan view. The frame is supported from a face plate or helmet which the user wears in order to support the weight of the night vision device. The conventional ANVIS 6 includes an interpupillary distance adjustment mechanism with a pair of transversely aligned rotatable shafts near the front of the frame. Each of the rotatable shafts is drivingly coupled to the other at adjacent ends, and each extends laterally within the rectangular frame above one of the monocular scopes. Each shaft defines a respective thread portion of opposite hand, and the rectangular frame slidably carries a pair of depending monocular mounts each threadably engaging one of the threaded shafts. One of the threaded shafts includes an outwardly projecting knob, rotation of which rotates both shafts and simultaneously moves the monocular mounts symmetrically together or apart to adjust interpupillary distance to the preferences of the user.
The conventional ANVIS 6 also includes a tilting mechanism which includes an elongate eccentric bushing device which is rotatable in the rectangular frame. This rotatable bushing carries the threaded shafts of the interpupillary adjustment mechanism, and moves these shafts in an arcuate path to tilt the monocular mounts relative to the rectangular frame about a slide and pivot shaft. This slide and pivot shaft is carried adjacent to the rear of the frame.
With the conventional ANVIS 6, the interpupillary adjustment mechanism is lubricated with grease and is protected from environmental dust by four bellows type dust seals which extend along the threaded shafts between the monocular mounts and the frame. At the monocular mounts, the conventional ANVIS 6 includes a respective counter bore, which encroaches on the threaded length of the monocular mount, and into which the adjacent end of the bellows dust seal is received.
A persistent complaint about the conventional ANVIS 6 night vision device is that the monocular scopes wobble from side to side on the frame. This wobble is accentuated when the night vision device is used in an environment of high vibration, such as in a helicopter. In such an environment, the user of the night vision device depends heavily on the quality of the night vision image provided to gain a sense of depth perception. Understandably, when the night vision scopes wobble on their support frame the quality of image provided to the user is greatly compromised.
Another deficiency of the conventional ANVIS 6 type of night vision device relates to the short life and deterioration of the bellows type of dust seals. When these seals deteriorate sufficiently they allow entry of dust into the interpupillary adjustment mechanism. This environmental dust along with the original grease lubrication forms a kind of abrasive paste, which very quickly causes great wear in the monocular mounts and their respective threaded support shafts. Of course, such wear aggravates the already wobble-prone support of the monocular mounts so that the quality of image provided to a user is very poor, especially in a high vibration environment.